GB2559705A - Absorbent article - Google Patents

Abstract

In the present invention, a surface sheet (2) comprises a laminated body of a first sheet and a second sheet. The laminated body has a plurality of joining portions that partially join the first sheet and the second sheet. The first sheet forms a plurality of protrusions which protrude in a direction away from the second sheet and toward the wearer's body in locations other than the joining portions. The surface sheet (2) has a central area (S) and a pair of side areas (M) adjoining the central area (S). The shapes and/or arrangement patterns of the joining portions are different in the central area (S) and the side areas (M). The area ratio of the joining portions is substantially the same in the central area (S) and the side areas (M). The number of the joining portions per unit area is greater in the side areas (M) than in the central area (S).

Description

(54) Title ofthe Invention: Absorbent article Abstract Title: Absorbent article (57) In the present invention, a surface sheet (2) comprises a laminated body of a first sheet and a second sheet. The laminated body has a plurality of joining portions that partially join the first sheet and the second sheet. The first sheet forms a plurality of protrusions which protrude in a direction away from the second sheet and toward the wearer's body in locations other than the joining portions. The surface sheet (2) has a central area (S) and a pair of side areas (M) adjoining the central area (S). The shapes and/or arrangement patterns of the joining portions are different in the central area (S) and the side areas (M). x The area ratio ofthe joining portions is substantially the same in the central area (S) and the side areas (M). The number of the joining portions per unit area is greater in the side areas (M) than in the central area (S).

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DESCRIPTION

Title of Invention: ABSORBENT ARTICLE

Technical Field [0001]

The present invention relates to various types of absorbent articles such as disposable diapers and sanitary napkins.

Background Art [0002]

A technique for an absorbent article is known in which the skin-facing surface side of the topsheet is formed to have a three-dimensional shape in regards to reducing the contact area and friction between the topsheet and the skin of the wearer and improving the texture and the air permeability when the absorbent article is worn. For example, Patent Literature 1 discloses a topsheet 2 of an absorbent article 1 that includes a large number of projections 21 that have a shape elongated in a lengthwise direction of the absorbent article in a central region 2c that is provided at the center in the lengthwise direction, and a large number of projections 22 that have a shape elongated in a width direction of the absorbent article in end regions 2a and 2b that are provided on the front and back sides of the central region 2c. The projections 21 and 22 in the central region 2c and the end regions 2a and 2b are provided in a dispersed manner in the lengthwise direction and the width direction of the absorbent article 1. The topsheet 2 includes a first non-woven fabric 23 on which projections 21 and 22 are formed, and a second non-woven fabric 24 that is substantially flat and is bonded to the first non-woven fabric 23 at portions other than the projections 21 and 22 of the first non-woven fabric 23. Patent Literature 1 teaches that the absorbent article 1 that includes such a topsheet 2 has excellent absorption performance and excellent leakage prevention performance.

[0003]

Patent Literature 2 discloses a topsheet 2 of an absorbent article 1 in which a large number of projections 21 are formed in a dispersed manner in a lengthwise direction and a width direction of the absorbent article in a central region 2a that is provided at the center and extends in the lengthwise direction, and a plurality of projection rows R1 to R3 are formed in the width direction in side regions 2b and 2b that are provided on the right and left sides of the central region 2a, each projection row including a large number of projections 22 that are aligned in the lengthwise direction. The topsheet 2 includes a first non-woven fabric 22 that is shaped to have projections and recessions, and a second non-woven fabric 23 that is substantially flat and is bonded to the first non-woven fabric 22 at all or some of the depressions 22a of the first non-woven fabric 22. Patent Literature 2 teaches that the absorbent article 1 that includes such a topsheet 2 has excellent leakage prevention performance, and it is possible to effectively prevent both leakage from the sides and leakage from the front and back ends.

Citation List

Patent Literature [0004]

Patent Literature 1: JP 2009-136349A

Patent Literature 2: JP 2009-148445A

Summary of Invention [0005]

As disclosed in Patent Literatures 1 and 2, in order to improve the softness of the topsheet that is composed of a stack of two non-woven fabrics that are bonded to each other, or to reduce the friction between the topsheet and the skin of the wearer, it is effective to set the bonding area ratio between the two non-woven fabrics to a low level. However, a reduction in the bonding area ratio often results in a reduction in the bonding strength between the two non-woven fabrics. A reduction in the bonding strength may lead to the non-woven fabrics separating from each other, and a gap being formed between the two non-woven fabrics when the absorbent article is worn. In particular, the separation and the creation of a gap are more likely to occur in the vicinity of a leg opening portion where the degree of contact with the skin of the wearer is high.

Means for Solving the Problems [0006]

The present invention provides an absorbent article including: a topsheet; a backsheet; and an absorbent member that is provided between the topsheet and the backsheet, wherein the topsheet includes a stack including a first sheet and a second sheet, the stack includes a plurality of bonding portions formed by partially bonding the first sheet and the second sheet and has a plurality of projections which protrude toward a body of a wearer, the projections being formed in such a manner that portions of the first sheet other than the bonding portions protrude in a direction away from the second sheet and, the topsheet includes a central region that is located at a center in a width direction of the topsheet and that extends in a lengthwise direction thereof, and a pair of side regions that extend in the lengthwise direction, the side region being adjacent to the central region, a shape and/or an arrangement pattern of the bonding portions are different between the central region and the side regions, an area ratio of the bonding portions is substantially the same between the central region and the side regions, and the number of the bonding portions per unit area is greater in the side regions than in the central region.

Brief Description of Drawings [0007] [Fig. 1] Fig. 1 is a plan view of a disposable diaper that is an embodiment of an absorbent article according to the present invention in its laid-out state in which elastic members are uncontracted and flattened out, as viewed from a topsheet that is a skin-facing surface of the diaper.

[Fig. 2] Fig. 2 is a cross-sectional view in a thickness direction schematically showing a cross section taken along the line II-II shown in Fig. 1.

[Fig. 3] Fig. 3 is a partial plan view of the skin-facing surface of the topsheet of the diaper shown in Fig. 1.

[Fig. 4] Fig. 4 is an enlarged plan view of a relevant part of Fig. 3.

[Fig. 5] Fig. 5 is a schematic diagram showing an example of a cross-sectional structure of a first fiber or a second fiber that is used in the topsheet of the absorbent article according to the present invention.

[Fig. 6] Figs. 6(a) and 6(b) are plan views showing topsheets according to other embodiments that can be used in the absorbent article of the present invention.

Description of Embodiments [0008]

The present invention relates to improving a topsheet of an absorbent article that is composed of a stack of two sheets, and more specifically to an absorbent article that includes a topsheet that has a good texture and in which the two sheets are unlikely to separate from each other and a gap is unlikely to form between the two sheets.

[0009]

Hereinafter, the absorbent article according to the present invention will be described by way of preferred embodiments of the present invention with reference to the drawings. Figs. 1 and 2 show a disposable diaper 1 that is an embodiment of the absorbent article according to the present invention. The diaper 1 includes a front portion IF that is to be placed on an abdominal side of a wearer when the diaper is worn, a rear portion 1R that is to be placed on a dorsal side of the wearer, and a crotch portion 1M that is provided between the front portion IF and the rear portion 1R. The diaper 1 has a longitudinal direction X that extends from the front portion IF to the rear portion 1R via the crotch portion 1M and corresponds to the front-back direction of the wearer, and a lateral direction Y that is perpendicular to the longitudinal direction X. The front portion IF, the crotch portion 1M, and the rear portion 1R respectively correspond to regions obtained by dividing the diaper 1 in the longitudinal direction X into three equal parts. The crotch portion 1M includes a waste discharging portion-facing portion that is to be placed facing the waste discharging portion of the wearer when the diaper 1 is worn, and the waste discharging portion-facing portion is usually provided at or near the center of the diaper 1 in the longitudinal direction X.

[0010]

As shown in Figs. 1 and 2, the diaper 1 includes an absorbent member 4 that includes an absorbent core 40, a liquid permeable topsheet 2 that is provided on the skin-facing surface side of the absorbent member 4 and can come into contact with the skin of the wearer when the diaper is worn, and a liquid-impermeable or water-repellent backsheet 3 that is provided on the non-skin-facing surface side of the absorbent member 4. As viewed in plan as shown in Fig. 1, the diaper 1 has an elongated hourglass shape in which a central portion in the longitudinal direction X where the crotch portion 1M is provided is curved inward and is elongated in one direction, specifically, the longitudinal direction X. The topsheet 2 has dimensions that are substantially equal to or slightly larger than the dimensions of the absorbent member 4. The backsheet 3 has dimensions larger than the dimensions of the absorbent member 4. Also, the dimensions of the backsheet 3 are larger than those of the topsheet 2. The backsheet 3 extends outward from the peripheral edge of the absorbent member 4, and forms an outer shape of the diaper 1 in its laid-out and uncontracted state as shown in Fig. 1. As the backsheet 3, any type of backsheet that is conventionally used in this type of absorbent article can be used without any limitation, and it is possible to use a resin film, a laminate of a resin film and a non-woven fabric, or the like. The backsheet 3 may be air permeable.

[0011]

In this specification, the term skin-facing surface refers to a surface of an absorbent article or its constituent member (for example, the absorbent member 4) that is provided to face the skin of the wearer when the absorbent article is worn, or in other words, a surface that is relatively close to the skin of the wearer. The term non-skin-facing surface refers to a surface of an absorbent article or its constituent member that is provided to face the side opposite to the skin of the wearer when the absorbent article is worn, or in other words, a surface that is relatively far from the skin of the wearer. As used herein, the expression when an absorbent article (or diaper) is worn means a normal and properly worn position, or in other words, a state in which the correctly worn position of the absorbent article (or diaper) is maintained, and does not encompass a state in which the absorbent article (or diaper) is out of the correctly worn position.

[0012]

Side sheets 5 are provided on the right and left sides in the longitudinal direction X on the topsheet 2 side of the diaper 1. Each side sheet 5 includes an inner edge portion that extends in the longitudinal direction X, and an outer edge portion that is located on the outer side in the lateral direction Y with respect to the inner edge portion, and extends in the longitudinal direction X. As viewed in plan as shown in Fig. 1, the inner edge portion overlaps the absorbent member 4, and as shown in Fig. 2, the outer edge portion extends outward in the lateral direction Y from a side edge of the absorbent member 4 that extends in the longitudinal direction X, and is bonded to the backsheet 3. Between the side sheet 5 and the backsheet 3 in each of right and left leg portions that are to be placed around the legs of the wearer, an elastic member 50 in the form of strings is fixed in its stretched state so as to extend in the longitudinal direction X. With this configuration, when the diaper 1 is worn, a pair of legs gathers are formed in the leg portions of the diaper 1 as a result of the elastic members 50 contracting. Also, in the inner edge portion of each side sheet 5, an elastic member 51 in the form of strings is fixed in its stretched state so as to extend in the longitudinal direction X. With this configuration, when the diaper 1 is worn, due to the elastic members 51 contracting, at least in the crotch portion 1M, the side sheets 5 each form an anti-leak cuff as a result of the inner edge portion standing upright toward the skin of the wearer from the bonding portion between the side sheet 5 and the backsheet 3. The anti-leak cuffs can prevent a waste liquid such as urine from flowing outward in the lateral direction Y, or in other words, so-called side leakage. The topsheet 2, the backsheet 3, the absorbent member 4, the side sheets 5, and the elastic members 50 and 51 are bonded to each other by a known bonding means such as a hot melt adhesive or the like.

[0013]

The diaper 1 is a so-called open-type disposable diaper. As shown in Fig. 1, a pair of fastening tapes 6 and 6 are provided at two side edge portions that extend in the longitudinal direction X of the rear portion 1R of the diaper 1. A fastening portion (not shown) that is a male member of a mechanical hook-and-loop fastener is attached to each fastening tape 6. Also, in the non-skin-facing surface of the front portion IF of the diaper 1, a fastened region 7 that is a female member of the mechanical hook-and-loop fastener is formed. The fastened region 7 is formed by bonding and fixing the female member of the mechanical hook-and-loop fastener to the non-skin-facing surface of the backsheet 3 that forms the non-skin-facing surface of the front portion IF by a known bonding means such as, for example, an adhesive or heat sealing, and is configured to removably receive the fastening portions of the fastening tapes 6.

[0014]

As viewed in plan view as shown in Fig. 1, the absorbent member 4 has a shape that is elongated in the longitudinal direction X, and extends from the front portion IF to the rear portion 1R. The absorbent member 4 includes: a liquid retainable absorbent core 40 that contains an absorbent material; and a core wrap sheet 45 that covers a skin-facing surface 40a and a non-skin-facing surface 40b of the absorbent core 40. The absorbent core 40 and the core wrap sheet 45 are bonded by a known bonding means such as a hot melt adhesive. The absorbent member 4 (the absorbent core 40) is symmetric about an imaginary line (not shown) that divides the diaper 1 into halves in the lateral direction Y and that extends in the longitudinal direction X.

[0015]

The absorbent core 40 may have a monolayer structure. Alternatively, the absorbent core 40 may have a multilayer structure. As viewed in plan as shown in Fig. 1, the absorbent core 40 has an hourglass shape in which a central portion in the lengthwise direction, in other words the longitudinal direction X, is curved inward. The absorbent core 40 is formed by stacking fibers of a core forming material that contains an absorbent material. As the absorbent material, an absorbent material that is conventionally used to form this type of absorbent core can be used without a particular limitation. For example, it is possible to use wood pulp, hydrophilic fibers such as synthetic fibers that have been treated with a hydrophilizing agent, and absorbent polymer particles. That is, the absorbent core 40 may be made of a fiber stack of hydrophilic fibers, or absorbent polymer particles that are supported on the fiber stack.

[0016]

As the core wrap sheet 45, a water permeable sheet material can be used. As the core wrap sheet 45, for example, paper, non-woven fabric, and the like can be used. In the diaper 1 according to the present embodiment, the core wrap sheet 45 is a single continuous core wrap sheet 45 that has a width that is twice or more and three times or less of the length of the absorbent core 40 in the lateral direction Y. As shown in Fig. 2, the single core wrap sheet 45 covers the entire skin-facing surface 40a of the absorbent core 40, and extends outward in the lateral direction Y from two side edges of the absorbent core 40 that extend in the longitudinal direction X, and extension portions are bent downward of the absorbent core 40 to cover the entire non-skin-facing surface 40b of the absorbent core 40. Of course, the configuration of the core wrap sheet 45 is not limited thereto. For example, the core wrap sheet 45 may be composed of two separate sheets of a skin-side core wrap sheet that covers the skin-facing surface 40a of the absorbent core 40 and a non-skin-side core wrap sheet that covers the non-skin-facing surface 40b of the absorbent core 40.

[0017]

As shown in Fig. 3, the topsheet 2 disposed on the skin-facing surface 40a side of the absorbent member 4 includes a central region S, and a pair of side regions M and M that are located on both sides of the central region S. The central region S is located at the center in the width direction (i.e., the lateral direction Y) of the diaper 1, and extends in the lengthwise direction (i.e., the longitudinal direction X) of the diaper 1. The pair of side regions M and M are adjacent to the central region S, and extend in the lengthwise direction (i.e., the longitudinal direction X) of the diaper 1. The central region S and the side regions M are preferably formed at least in the crotch portion 1M, more preferably formed to extend from the crotch portion 1M to either one or both of the front portion IF and the rear portion 1R, even more preferably formed to extend over the full length of the absorbent member 4, and even much more preferably formed over the full length of the diaper 1.

[0018]

The central region S and the side regions M can be distinguished from each other by the shape and/or the arrangement pattern of bonding portions, which will be described later. The width of the central region S is preferably 30% or more of the width of the topsheet 2, and more preferably 40% or more. Also, the width of the central region S is preferably 70% or less, and more preferably 60% or less. Furthermore, the width of the central region S is preferably 30% or more and 70% or less of the width of the topsheet 2, and more preferably 40% or more and 60% or less. The width of each side region M is preferably 15% or more of the width of the topsheet 2, and more preferably 20% or more. Also, the width of each side region M is preferably 35% or less, and more preferably 30% or less. Furthermore, the width of each side region M is preferably 15% or more and 35% or less of the width of the topsheet 2, and more preferably 20% or more and 30% or less. The total width of the side regions M is preferably 30% or more of the width of the topsheet 2, and more preferably 40% or more. Also, the total width of the side regions M is preferably 70% or less, and more preferably 60% or less. Furthermore, the total width of the side regions M is preferably 30% or more and 70% or less of the width of the topsheet 2, and more preferably 40% or more and 60% or less.

[0019]

The topsheet 2 is composed of a stack including a first sheet and a second sheet. The first sheet is provided on the wearer's body side when the diaper 1 is worn. The second sheet is provided on the absorbent member 4 side. As shown in Fig. 4 that is an enlarged view of a relevant part of Fig. 3, the topsheet 2 includes, in the central region S and each side region M, a plurality of bonding portions Mil, M12, Sil, and S12 formed by partially bonding the stack of the first sheet and the second sheet through embossing or ultrasonic processing, and has a plurality of projections M21, S21, and S22 which protrude toward the skin of the wearer, the projections being formed in such a manner that the portions of the first sheet other than the bonding portions Mil, M12, Sil, and S12 protrude in a direction away from the second sheet. The topsheet 2 is also configured such that, in the central region S and each side region M, its second sheet-side surface is substantially flat, and large height undulations are formed on its first sheet-side surface.

[0020]

The bonding portions included in the central region S of the topsheet 2 include a central first bonding portion Sil and a central second bonding portion S12. The central first bonding portion Sil and the central second bonding portion S12 have rectangular shapes with sides extending in the longitudinal direction X and sides extending in the lateral direction Y, and the shape of the central first bonding portion Sil is different from the shape of the central second bonding portion S12. The central first bonding portions

511 are disposed so as to form first bonding portion rows S31 where the central first bonding portions Sil are arranged with a predetermined distance therebetween in the longitudinal direction X. The central second bonding portions S12 are also disposed so as to form a second bonding portion row S32 and a third bonding portion row S33 where the central second bonding portions S12 are arranged with a predetermined distance therebetween in the longitudinal direction X. The second bonding portion row S32 and the third bonding portion row S33 are alternately disposed between the first bonding portion rows S31 adjacent to one another. A pitch, in the longitudinal direction X, of the central second bonding portions S12 included in the second bonding portion row S32 is the same as a pitch, in the longitudinal direction X, of the central second bonding portions S12included in the third bonding portion row S33. The central second bonding portions

512 included in the second bonding portion row S32 are shifted by half pitch from the central second bonding portions S12 included in the third bonding portion row S33. As a result of the central first bonding portions Sil and the central second bonding portions

S12 being disposed as described above, the projections included in the central region S include a central first projection S21 and a central second projection S22. The central first projection S21 has a substantially elliptical shape in plan view in which the length in the lateral direction Y is longer than the length in the longitudinal direction X. The central second projection S22 has a substantially circular shape in plan view in which the length in the lateral direction Y is substantially the same as the length in the longitudinal direction X. When the topsheet 2 is viewed in the longitudinal direction X, a first projection row S34, in which the central first projections S21 and the central second projections S22 are alternately disposed in the longitudinal direction X, is formed in the central region S. The first projection row S34 is located at the same position as the second bonding portion row S32 described above. Also, when the topsheet 2 is viewed in the longitudinal direction X, a second projection row S35, in which only the central second projections S22 are disposed in the longitudinal direction X, is formed in the central region S. The second projection row S35 is located at the same position as the third bonding portion row S33 described above. The term substantially elliptical shape is a concept that encompasses a complete elliptical shape and an elongated circular shape. The expression substantially circular shape in which the length in the lateral direction Y is substantially the same as the length in the longitudinal direction X encompasses both a perfect circular shape and an elliptical shape in which the length in the longitudinal direction X is within a range of ±10% of the length in the lateral direction Y.

[0021]

The bonding portions included in each side region M of the topsheet 2 include a side first bonding portion Mil and a side second bonding portion M12. The side first bonding portion Mil and the side second bonding portion M12 have rectangular shapes with sides extending in the longitudinal direction X and sides extending in the lateral direction Y, and the shape of the side first bonding portion Ml 1 is different from the shape of the side second bonding portion M12. The side first bonding portions Mil are disposed so as to form a fourth bonding portion row M31 where the side first bonding portions Mil are arranged with a predetermined distance therebetween in the longitudinal direction X. The side second bonding portions M12 are also disposed so as to form fifth bonding portion rows M32 where the side second bonding portions M12 are arrange with a predetermined distance therebetween in the longitudinal direction X. The fourth bonding portion row M31 and the fifth bonding portion row M32 are alternately disposed in the lateral direction Y. A pitch of the side first bonding portions Ml 1 included in the fourth bonding portion row M31 is the same as a pitch of the side second bonding portions M12 included in the fifth bonding portion row M32. The side first bonding portions Mil included in the forth bonding portion row M31 are shifted by half pitch from the side second bonding portions M12 included in the fifth bonding portion row M32. As a result, the projections included in the side regions M include only one type of projection, namely side projections M21. Each side projection M21 is formed within a region surrounded by four bonding portions: two side first bonding portions Mil that are adjacent in the longitudinal direction X; and two side second bonding portions M12 that are adjacent in the lateral direction Y. The side projections M21 have a substantially circular shape, in plan view, in which the length in the lateral direction Y is substantially the same as the length in the longitudinal direction X. When the topsheet 2 is viewed in the lateral direction Y, a third projection row M33 and a fourth projection row M34, in each of which the side projections M21 are disposed in the lateral direction Y, are formed in the side region M. A pitch of the side projections M21 included in the third projection row M33 is the same as a pitch of the side projections M21 included in the fourth projection row M34. The side projections M21 included in the third projection row M33 are shifted by half pitch from the side projections M21 included in the fourth projection row M34..

[0022]

In the central region S, the height of the central first projections S21 may be the same as or different from the height of the central second projections S22. From the viewpoint of improving the external appearance and the tactile impression, the height of the central first projections S21 is preferably different from the height of the central second projections S22. In the case where the projections S21 and S22 have different heights, the height of the central first projections S21 may be higher than the height of the central second projections S22. Alternatively, the height of the central second projections S22 may be higher than the height of the central first projections S21. By configuring two types of projections to have different heights, portions that give different tactile impressions are alternately provided, the portions gives a better texture when the portions are touched with a finger, as compared with the case where one type of projection that has the same height are provided. Also, with this configuration, leakage can be reduced because, when discharged urine flows along the surface of the topsheet 2, the resistance to urine moving from low projections to high projections is increased, which makes it difficult for the urine to flow. With respect to the side projections M21 formed in the side regions M, each side projection M21 may have the same height as that of the central first projections S21 and the central second projections S22, or may have a height different from that of the central first projections S21 and the central second projections S22. For example, the height of the side projections M21 may be the same as that of either one of the central first projections S21 and the central second projections S22, may be the same as those of the central first projections S21 and the central second projections S22, or may be different from those of the central first projections S21 and the central second projections S22. In each side region M, the topsheet 2 is likely to separate due to the movement of the wearer's leg. For this reason, from the viewpoint of suppressing the separating of the topsheet 2, the side projections M21 provided in each side region M are preferably composed of one type of projection. Also, the height of the side projections M21 in the side regions M is preferably lower than or the same as the heights of the central first projections S21 and the central second projections S22 in the central region S that is required to have a better texture.

[0023]

In the topsheet 2, the shape and/or the arrangement pattern of the bonding portions Sil, S12, Mil, and M12 are different between the central region S and the side regions M. Specifically, at least either one of the shape or the arrangement pattern of the bonding portions Sil, S12, Mil, and M12 is different between the central region S and each side region M. To be more specific, the central region S and each side region M are formed to have any one of the following configurations: (i) the arrangement pattern of the bonding portions is the same, but the bonding portions have different shapes; (ii) the bonding portions have the same shape, but the arrangement pattern of the bonding portions is different; and (iii) the arrangement pattern of the bonding portions is different, and the bonding portions have different shapes. By configuring the central region S and each side region M differently as described above, contact between the topsheet 2 and the skin of the wearer can be appropriately controlled, and the external appearance can be changed significantly, it is preferable that the shape and arrangement pattern of the bonding portions are different. In the embodiment shown in Figs. 3 and 4, in the central region S and the side regions M, the arrangement pattern of the bonding portions Sil, S12, Mil, and M12 is different, and the shape of the bonding portions Sil, S12, Mil, and M12 is also different.

[0024]

In the topsheet 2, in addition to the shape and/or the arrangement pattern of the bonding portions being different between the central region S and each side region M, the area ratio of the bonding portions is substantially the same between the central region S and each side region M. The area ratio (%) of the bonding portions refers to a value obtained by, in each of the central region S and the side regions M, dividing a total area of the bonding portions that are provided in a predetermined area by the predetermined area, and further multiplying by 100. The expression the area ratio of the bonding portions is substantially the same encompasses both the case where the area ratio of the bonding portions is the same between the central region S and each side region M, and the case where the area ratio in the side region M is within a range of ±15% of the area ratio in the central region S. That is, if the area ratio in the side region M is 0.85A% or more and 1.15A% or less, where the area ratio in the central region S is represented by A%, it can be said that the area ratio is substantially the same between the central region S and each side region M.

[0025]

Configuring the central region S and the side regions M so as to have substantially the same area ratio of the bonding portions provides an advantage in that the first sheet and the second sheet that constitute the topsheet 2 are unlikely to separate from each other when the diaper 1 is worn. It also provides another advantage in that little variation occurs in pressure when a roll is rotated to produce the topsheet 2 by adhesively attaching the first sheet and the second sheet to each other, and the linear pressure in the width direction of the roll can be made substantially the same between the central region S and the side regions M, which results in a significant improvement in processability. For example, holes are unlikely to be formed during the process of adhesively attaching the first sheet and the second sheet to each other. It is also possible to suppress wearing and cracking of the roll that is used to adhesively attach the first sheet and the second sheet to each other.

[0026]

Also, with the configuration in which the area ratio of the bonding portions is substantially the same between the central region S and each side region M, it is possible to obtain an advantage that is important to the absorbent article in that discharged urine can be uniformly absorbed over the entire surface of the absorbent member. In the present embodiment, a plurality of bonding portions Ml 1, M12, S11, and S12 are formed by partially bonding the stack of the first sheet and the second sheet through embossing or ultrasonic processing. In the bonding portions, the fibers of the non-woven fabrics that constitute the first sheet and the second sheet are made into a film in order to prevent the occurrence of separation and formation of a gap during use, and thus urine is not absorbed by the bonding portions. In a normally used state, urine is discharged to the central region S at a rate of 3 cc/sec or more and 20 cc/sec or less. Accordingly, not all of the urine can be absorbed by the central region S. It is therefore important that urine is instantaneously absorbed not only by the central region S but also by side regions M. If the area ratio of the bonding portions that are present in the central region S and the area ratio of the bonding portions that are present in the side regions M are different, nonuniformity occurs in the absorption rate of discharged urine in these regions, which makes it difficult to use the entire surface of the absorbent member uniformly and efficiently, and makes leakage likely to occur. In the present invention, because the area ratio of the bonding portions is the same between these regions, it is possible to prevent the occurrence of such a disadvantage. Also, the entire surface of the absorbent member is used uniformly and efficiently, and thus free moisture within the diaper (moisture that is not retained by the absorbent polymer particles) is reduced, and it is possible to suppress moisture from returning to the skin when the diaper is worn.

[0027]

Under the condition that the area ratio of the bonding portions is substantially the same between the central region S and each side region M, the area ratio of the bonding portions in the central region S and each side region M is preferably 10% or more, and more preferably 15% or more. Also, the area ratio of the bonding portions is preferably 40% or less, and more preferably 35% or less. The area ratio of the bonding portions is preferably 10% or more and 40% or less, and more preferably 15% or more and 35% or less. By setting the area ratio within the above-described range, the bonding strength between the two sheets can be sufficiently increased without reducing the texture and the absorption performance of the topsheet 2.

[0028]

In the topsheet 2, in addition to the shape and/or the arrangement pattern of the bonding portions being different between the central region S and each side region M, the number of bonding portions per unit area is greater in each side region M than in the central region S. With the configuration in which the number of bonding portions per unit area is greater in each side region M than in the central region S, the following advantages (a) and (b) can be obtained.

(a) The degree of freedom of constituent fibers of the topsheet 2, or in other words, the mobility of fibers is higher in the central region S than in the side region M. As a result, the softness of the central region S is improved.

(b) The height difference between projections and depressions in the side region M is relatively low, and the degree of freedom of the fibers is reduced. As a result, breakage of the topsheet 2 in the side regions caused by movement of the wearer's legs is unlikely to occur. Also, setting the number of bonding portions in each side region M to be greater than in the central region S also provides an advantage in that vibration of both side portions of the roll during production is reduced, as a result of which processability is improved significantly. For example, holes are unlikely to be formed during the process of adhesively attaching the first sheet and the second sheet to each other. It is also possible to suppress wearing and cracking of the roll that is used to adhesively attach the first sheet and the second sheet to each other.

[0029]

The topsheet 2 preferably has a relationship C > D, wherein C represents the area of the bonding portions Sil and S12 that has the largest area among the bonding portions formed in the central region S, and D represents the area of the bonding portions Ml 1 and M12 that has the largest area among the bonding portions formed in the side region M. With the configuration in which the area of the bonding portions formed in the central region S is larger than the area of the bonding portions formed in the side regions M, the number of bonding portions formed in the central region S can be easily made less than the number of bonding portions formed in the side regions M. Accordingly, irregular wrinkles are unlikely to occur in the central region S when the diaper 1 is worn. The occurrence of irregular wrinkles makes it easy for urine and excrement to flow along the wrinkles, which may result in leakage. To address this, by suppressing the occurrence of wrinkles, liquid leakage can be suppressed.

[0030]

From the viewpoint of further suppressing the occurrence of wrinkles, the area D is preferably 80% or less of the area C, and more preferably 70% or less. Also the area D is preferably 20% or more of the area C, and more preferably 30% or more. The area D is preferably 20% or more and 80% or less of the area C, and more preferably 30% or more and 70?^zo or less.

[0031]

The proportion of the total area of the bonding portions of the area C to the total area of the bonding portions in the central region S is preferably 20% or more, and more preferably 30% or more. The upper limit of the proportion is preferably 80%, and more preferably 70%. On the other hand, the proportion of the total area of the bonding portions of the area D to the total area of the bonding portions in each side region M is preferably 80% or more, and more preferably 90% or more. The upper limit of the proportion is preferably 100%.

[0032]

The topsheet 2 preferably has a relationship E > F, wherein E represents the length, in the longitudinal direction X, of the bonding portions Sil and S12 that has the longest length among the bonding portions formed in the central region S, and F represents the length, in the lengthwise direction, of the bonding portions Mil and M12 that has the longest length among the bonding portions formed in each side region M. With this configuration, when the diaper 1 is worn, wrinkles are likely to occur in an orderly manner in the central region S, the wrinkles being caused by the central region S receiving a force acting inward in the lateral direction from the wearer's thighs. To rephrase, irregular wrinkles are unlikely to occur in the central region S, as a result of which liquid leakage is suppressed.

[0033]

From the viewpoint of causing wrinkles to occur in a more orderly manner, the length F is preferably 80% or less of the length E, and more preferably 70% or less. Also, the length F is preferably 20% or more of the length E, and more preferably 30% or more. The length F is preferably 20% or more and 80% or less of the length E, and more preferably 30% or more and 70% or less.

[0034]

The proportion of the total area of the bonding portions of the length E to the total area of the bonding portions in the central region S is preferably 20% or more, and more preferably 30% or more. The upper limit of the proportion is preferably 100%, and more preferably 80%. On the other hand, the proportion of the total area of the bonding portions of the length F to the total area of the bonding portions in each side region M is preferably 60% or more, and more preferably 80% or more. The upper limit of the proportion is preferably 100%, and more preferably 90%.

[0035]

In the topsheet 2, it is preferable that each side region M of the topsheet 2 has higher shearing stress than the central region S of the topsheet 2. The shearing stress is an indication of the softness of the projections formed in the central region S and each side region M. The smaller the value of the shearing stress, the softer the projections. Accordingly, the fact that the shearing stress is higher in each side region M than that in the central region S indicates that the projections in the central region S are softer than those in the side regions. With this configuration, the projections in the central region S that is the most dominantly soft region can be made softer, and it is thereby possible to provide a comfortably fitting diaper 1.

[0036]

The shearing stress can be measured using the following method.

A test specimen is obtained by cutting a topsheet that serves as a measurement target into a rectangular shape in plan view with a longitudinal length of 50 mm and a lateral length of 30 mm. Next, an adhesive tape (product name: No. 500, available from Nitto Denko Corporation) that has the same shape and dimensions as those of the test specimen is placed on a PET film (product name: Star OHP Film, available from Star Corporation) so as to produce a stack (A). Then, the non-projection side of the test specimen is placed on the adhesive tape side of the stack (A) so as to obtain a stack (B). A roller that has a weight of 1 kg is moved back and forth five times on the stack (B) so as to compression bond the adhesive tape and the test specimen included in the stack (B). A male member (product name: 1600 PPI, available from 3M Company) of a mechanical fastener that has a shape and dimensions that are sufficient to cover the entire test specimen is prepared as an attachment piece, and the attachment piece is compression bonded to the projection side of the test specimen included in the stack (B) via the hook member on the attachment piece under a load of 1.5 kPa so as to obtain a measurement sample. The obtained measurement sample is placed between chucks (with a chuck-to-chuck distance of 150 mm) of a tensile testing machine (Autograph AG-X available from Shimadzu Corporation), and the measurement sample is subjected to 180 degree peeling. The 180 degree peeling is performed by pulling the stack (B) at one end in the longitudinal direction of the measurement sample and the attachment piece on the other end that are held respectively by the chucks of the tensile testing machine apart from each other in 180-degree opposite directions. The pulling rate is set to 300 mm/min, and the maximum pulling load at this time is recorded. As measurement sites, for each diaper that serves as a test specimen, a total of six sites (the front side and the rear side in the lengthwise direction of the diaper, and the left side, the right side, and the center in the transverse direction of the diaper) are selected. Measurement is performed on a total of three diapers, and the average value thereof is defined as the shearing stress (unit: N) of the topsheet that is a measurement target.

[0037]

The shearing stress of the central region S takes a value of, preferably 25 N or more, and more preferably 30 N or more. Also, the shearing stress of the central region S takes a value of, preferably 34 N or less, and more preferably 33 N or less. The shearing stress of the central region S takes a value of, preferably 25 N or more and 34 N or less, and more preferably 30 N or more and 33 N or less. On the other hand, the shearing stress of each side region M takes a value of, preferably 33 N or more, and more preferably 35 N or more under the condition that the shearing stress of each side region M is higher than the shearing stress of the central region S. Also, the shearing stress of each side region M takes a value of, preferably 45 N or less, and more preferably 40 N or less. The shearing stress of each side region M takes a value of, preferably 33 N or more and 45 N or less, and more preferably 35 N or more and 40 N or less.

[0038]

In order to configure the central region S and each side region M to have different shearing stress values, for example, the pattern of bonding portions may be changed between the central region S and each side region M, or the bonding strength of bonding portions may be changed between the central region S and each side region M. For example, it is assumed that the projections S21 and S22 are present in the central region S, and the projections M21 are present in each side region M (see Fig. 4). At this time, it is important to satisfy a relationship Smax > M_max, wherein Smax represents the area of the projection (projections S21 in Fig. 4) that has the largest area among the projections in the central region S, and Mmax represents the area of the projection (projections M21) that has the largest area among the projections in the side region M. By satisfying the relationship, the degree of freedom (mobility) of the fibers in the central region S becomes relatively higher than that of the fibers in the side regions M, and softness is enhanced more significantly.

[0039]

A topsheet 2 configured as described above can be produced in accordance with, for example, the method for producing a composite sheet disclosed in JP 2015-112343 A. To be specific, for example, a strip-shaped first sheet is fed between a first roll and a second roll whose circumferential surfaces are shaped to be engageable with each other, the first sheet is deformed to have projections and recessions, then, the first sheet is moved along the circumferential surface portion of the first roll from the engaging portion, and thereafter a second sheet is fed such that the second sheet is placed on the first sheet. The two sheets are compressed under heat between the projections on the first roll and a heat roll so as to partially bond the sheets. At this time, the shape of the projections and recessions of the first roll and the second roll, and the pattern of bonding portions formed by the first roll and the heat roll are varied between the central portion and the side portions of the first sheet. At the time when the first sheet is deformed to have projections and recessions by feeding the first sheet into the engaging portion between the first roll and the second roll, it is preferable that the first sheet is pulled in a direction toward the inside of the rolls so as to facilitate the deformation of the first sheet to have projections and recessions.

[0040]

The first sheet and the second sheet that constitute the topsheet 2 are made of sheet materials. As the sheet materials, it is possible to use, for example, fiber sheets such as non-woven fabrics, woven fabrics, and knitted fabrics, films, and the like. From the viewpoint of texture and the like, it is preferable to use fiber sheets. In particular, it is preferable to use non-woven fabrics. The sheet material that constitutes the first sheet and the sheet material that constitutes the second sheet may be of the same type, or may be of different types. However, from the viewpoint of obtaining strong seal strength, it is preferable that the sheet material that constitutes the first sheet and the sheet material that constitutes the second sheet is of the same type.

[0041]

In the case where a non-woven fabric is used as the sheet material for each of the first sheet and the second sheet, examples of the non-woven fabric include an air-through non-woven fabric, a spunbond non-woven fabric, a spunlace non-woven fabric, a melt-blown non-woven fabric, a resin bonded non-woven fabric, and a needle punched non-woven fabric. It is also possible to use a stack obtained by combining two or more of the non-woven fabrics listed above, or a stack obtained by combining a non-woven fabric as listed above with a film and the like. Among the non-woven fabrics listed above, it is preferable use an air-through non-woven fabric, or a spunbond non-woven fabric. In particular, the first sheet that is the sheet to be placed on the side that faces the wearer's skin when the diaper 1 is worn is preferably made of an air-through non-woven fabric.

[0042]

The non-woven fabrics that are used as the sheet materials for the first sheet and the second sheet independently have a basis weight of preferably 10 g/m² or more, and more preferably 15 g/m² or more, and preferably 40 g/m² or less, and more preferably 35 g/m² or less. The non-woven fabrics have a basis weight of 10 g/m² or more and 40 g/m² or less, and more preferably 15 g/m² or more and 35 g/m² or less.

[0043]

As the fibers that constitute such a non-woven fabric, fibers made of any type of thermoplastic resin can be used. Examples of the thermoplastic resin include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polyamides such as nylon 6 and nylon 66, poly (acrylic acid), polymethacrylic acid alkyl ester, poly (vinyl chloride), and polyvinylidene chloride. These resins may be used alone or as a blend containing a combination of two or more. Also, these resins may be used in the form of composite fibers such as core-in-sheath composite fibers or side-by-side composite fibers.

[0044]

In particular, the first sheet that is the sheet to be placed on the side that faces the wearer's skin when the diaper 1 is worn preferably contains a plurality of types of fibers. Particularly when the first sheet has a two-layer structure composed of an upper layer and a lower layer, it is preferable that either one of the upper layer and the lower layer contains a plurality of types of fibers. This configuration provides a high level of sense of cushioning created by the projections, and improves the smoothness of the projections. Furthermore, the standing ability of the projections and the collapse resistance of the projections when a load is applied are improved.

[0045]

The plurality of types of fibers preferably include at least two types of fibers of a first fiber and a second fiber. The first fiber and the second fiber preferably contain a high-melting point component, and a low-melting point component that has a melting point lower than that of the high-melting point component. In this case, the high-melting point component of the first fiber and the high-melting point component of the second fiber may be of the same type, or may be of different types. Also, the low-melting point component of the first fiber and the low-melting point component of the second fiber may be of the same type, or may be of different types. The first fiber and the second fiber are preferably distinguished from each other by changing the diameter ratio. In this specification, the term diameter ratio refers to the ratio of the diameter (pm) of the high-melting point component to the diameter of the low-melting point component in each of the first fiber and the second fiber. Regarding the diameter of the high-melting point component and the diameter of the low-melting point component, for example, in the case where the first and second fibers are core-in-sheath composite fibers, with its sheath resin being composed of a low-melting point component, and its core resin being composed of a high-melting point component, DI shown in Fig. 5 indicates the diameter of the low-melting point component Cl, and D2 indicates the diameter of the high-melting point component C2. Then, a diameter ratio AX between the high-melting point component C2 and the low-melting point component Cl in the X-th fiber can be calculated from the following equation. The term heat fusible fibers of the same type used herein refers to fibers that are made of the same resin and have the same structure. For example, if there are two core-in-sheath composite fibers composed of a high-melting point component and a low-melting point component, and the high-melting point component and the low-melting point component of the two composite fibers are made of the same resin, and have the same core/sheath diameter ratio, it can be said that the two composite fibers are heat fusible fibers of the same type. On the other hand, even if the high-melting point component and the low-melting point component are made of the same resin, if the diameter ratio is different, the two composite fibers are heat fusible fibers of different types. Also, the expression to contain a plurality of types of fibers means to contain heat fusible fibers of different types.

Diameter ratio AX of X-th fiber = diameter DI (pm) of low-melting point component of X-th fiber = diameter D2 (pm) of high-melting point component of X-th fiber [0046]

In the present invention, as described above, it is preferable that a diameter ratio Al of the first fiber and a diameter ratio A2 of the second fiber are different. The value of A2/A1 that is the ratio of A2 to Al is preferably less than 1, more preferably 0.99 or less, and even more preferably 0.91 or less. Also, the value of A2/A1 is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. By setting the ratio between Al and A2 as described above, the sense of cushioning created by the projections is further enhanced, and the smoothness of the projections is further improved. Furthermore, the standing ability of the projections and the collapse resistance of the projections when a load is applied are further improved. For example, the value of A2/A1 is preferably 0.5 or more and less than 1, more preferably 0.6 or more and 0.99 or less, and even more preferably 0.7 or more and 0.91 or less.

[0047]

The ratio between the diameter ratio Al of the first fiber and the diameter ratio

A2 of the second fiber is as described above. The diameter ratio Al of the first fiber takes a value of, preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more. Also, the diameter ratio Al of the first fiber takes a value of, preferably 2.0 or less, more preferably 1.9 or less, and even more preferably 1.8 or less. To be specific, the diameter ratio Al of the first fiber takes a value of, preferably 1.1 or more and 2.0 or less, more preferably 1.2 or more and 1.9 or less, and even more preferably 1.3 or more and 1.8 or less.

[0048]

On the other hand, the diameter ratio A2 of the second fiber takes a value of, preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more under the condition that the value of the diameter ratio A2 of the second fiber is smaller than that of the diameter ratio Al. Also, the diameter ratio A2 of the second fiber takes a value of, preferably 2.0 or less, more preferably 1.9 or less, and even more preferably 1.8 or less. To be specific, the diameter ratio A2 of the second fiber takes a value of, preferably 1.1 or more and 2.0 or less, more preferably 1.2 or more and 1.9 or less, and even more preferably 1.3 or more and 1.8 or less.

[0049]

Figs. 6(a) and 6(b) show topsheets 2 according to other embodiments. In a topsheet 2 according to an embodiment shown in Fig. 6(a), the bonding portions included in the central region S include central first bonding portions Sil and central second bonding portions S12 that have mutually different shapes. The central first bonding portions Sil are disposed so as to form first bonding portion rows S31 where the central first bonding portions Sil are arranged with a predetermined distance therebetween in the longitudinal direction X. Fikewise, the central second bonding portions S12 are also disposed so as to form second bonding portion rows S32 where the central second bonding portions S12 are arranged with a predetermined distance therebetween in the longitudinal direction X. Two first bonding portion rows S31 and one second bonding portion row S32 are combined as a group, and the group is repeatedly disposed in the lateral direction Y.

[0050]

On the other hand, the bonding portions included in each side region M includes only one type of bonding portion, namely, side first bonding portions Ml 1. The side first bonding portions Mil are disposed so as to form fourth bonding portion rows M31 where the side first bonding portions Mil are arranged with a predetermined distance therebetween in the longitudinal direction X. Also, the side first bonding portions Mil are disposed so as to form fifth bonding portion rows M32 where the side first bonding portions Mil are arranged with a predetermined distance therebetween in the longitudinal direction X. The pitch, in the longitudinal direction X, of the bonding portions 11 included in the fourth bonding portion rows M31 is different from the pitch, in the longitudinal direction X, of the bonding portions 11 included in the fifth bonding portion row M32. The pitch of the bonding portions 11 included in the fifth bonding portion row M32 is larger than the pitch of the bonding portions 11 included in the fourth bonding portion rows M31.

[0051]

In a topsheet 2 according to an embodiment shown in Fig. 6(b), the bonding portions included in the central region S includes central first bonding portions Sil and central second bonding portions S12 that have mutually different shapes. The central first bonding portions Sil are disposed so as to form first bonding portion rows S31 where the central first bonding portions Sil are arranged with a predetermined distance therebetween in the longitudinal direction X. Also, the central first bonding portions Sil are disposed so as to form second bonding portion rows S32 where the central first bonding portions Sil are arranged with a predetermined distance therebetween in the longitudinal direction X. The pitch, in the longitudinal direction X, of the central first bonding portions Sil included in the first bonding portion row S31 is the same as the pitch, in the longitudinal direction X, of the central first bonding portions Sil included in the second bonding portion row S32. The central first bonding portions Sil included in the first bonding portion row S31 are shifted by half pitch from the central first bonding portions Sil included in the second bonding portion row S32. On the other hand, the central second bonding portions S12 are disposed so as to form third bonding portion rows S33 where the central second bonding portions S12 are arranged with a predetermined distance therebetween in the longitudinal direction X. In the central region S, one first bonding portion row S31, one third bonding portion row S33, one first bonding portion row S31, one third bonding portion row S33, one second bonding portion row S32, and one third bonding portion row S33 are arranged in this order in the lateral direction Y, and are combined as a group, and the group is repeatedly disposed in the lateral direction Y.

[0052]

On the other hand, the bonding portions included in the side region M includes only one type of bonding portion, namely, side first bonding portions Ml 1. The side first bonding portions Mil are disposed so as to form fourth bonding portion rows M31 where the side first bonding portions Mil are arranged with a predetermined distance therebetween in the longitudinal direction X. Also, the side first bonding portions Mil are disposed so as to form fifth bonding portion rows M32 where the side first bonding portions Mil are arranged with a predetermined distance therebetween in the longitudinal direction X, thereby forming fifth bonding portion rows M32. The pitch, in the longitudinal direction X, of the bonding portions 11 included in the fourth bonding portion rows M31 is the same as the pitch , in the longitudinal direction X, of the bonding portions 11 included in the fifth bonding portion rows M32. The bonding portions 11 included in the fourth bonding portion rows M31 are shifted by half pitch from the bonding portions 11 included in the fifth bonding portion rows M32.

[0053]

In the case of the topsheets 2 according to the embodiments shown in Figs. 6(a) and 6(b) described above as well, it is preferable that the area ratio of the bonding portions is substantially the same between the central region S and each side region M, and it is preferable that the number of bonding portions per unit area is greater in each side region M than in the central region S. With the configuration described above, the topsheets 2 have a good texture, and it is unlikely that the two sheets will separate from each other and that a gap will occur between the two sheets.

[0054]

Up to here, the present invention has been described by way of preferred embodiments of the present invention. However, the present invention is not limited to the embodiments given above. For example, in the embodiments given above, an example was described in which the absorbent article according to the present invention is applied to an open-type disposable diaper. However, the present invention is also applicable to other disposable diapers such as, for example, a pull-on disposable diaper. Furthermore, the present invention is also applicable to absorbent articles other than disposable diapers such as, for example, a sanitary napkin, and an adult incontinence pad.

[0055]

For the embodiment described above, additional absorbent articles are further disclosed below by the present invention.

<1>

An absorbent article comprising: a topsheet; a backsheet; and an absorbent member that is provided between the topsheet and the backsheet, wherein the topsheet comprises a stack including a first sheet and a second sheet, the stack includes a plurality of bonding portions formed by partially bonding the first sheet and the second sheet, and has a plurality of projections which protrude toward a body of a wearer, the projections being formed in such a manner that portions of the first sheet other than the bonding portions protrude in a direction away from the second sheet and, the topsheet includes a central region that is located at a center in a width direction of the topsheet and that extends in a lengthwise direction thereof, and a pair of side regions that extend in the lengthwise direction, the side region being adjacent to the central region, a shape and/or an arrangement pattern of the bonding portions are different between the central region and the side regions, an area ratio of the bonding portions is substantially the same between the central region and the side regions, and the number of the bonding portions per unit area is greater in the side regions than in the central region.

<2>

The absorbent article as set forth in clause <1>, wherein the topsheet has a relationship C > D, wherein C represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region, and D represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions.

<3>

The absorbent article as set forth in clause <1> or <2>, wherein the topsheet has a relationship E > F, wherein E represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions.

<4>

The absorbent article as set forth in any one of clauses <1> to <3>, wherein the topsheet is configured such that each of the side regions of the topsheet has a higher shearing stress than the central region of the topsheet.

<5>

The absorbent article as set forth in any one of clauses <1> to <4>, comprising: a front portion that is to be placed on an abdominal side of a wearer when the absorbent article is worn;

a rear portion that is to be placed on a dorsal side of the wearer; and a crotch portion that is provided between the front portion and the rear portion, wherein the central region and the side regions are formed at least in the crotch portion.

<6>

The absorbent article as set forth in any one of clauses <1> to <5>, comprising: a front portion that is to be placed on an abdominal side of a wearer when the absorbent article is worn;

a rear portion that is to be placed on a dorsal side of the wearer; and a crotch portion that is provided between the front portion and the rear portion, wherein the central region and the side regions are preferably formed so as to extend from the crotch portion to either one or both of the front portion and the rear portion, more preferably formed to extend over the full length of the absorbent member, even more preferably formed over the full length of the absorbent article.

<7>

The absorbent article as set forth in any one of clauses <1> to <6>, wherein a width of the central region is preferably 30% or more of a width of the topsheet, more preferably 40% or more, and preferably 70% or less of a width of the topsheet, more preferably 70% or less.

<8>

The absorbent article as set forth in any one of clauses <1> to <7>, wherein a width of each of the side regions is preferably 15% or more and 35% or less of a width of the topsheet, and more preferably 20% or more and 30% or less.

<9>

The absorbent article as set forth in any one of clauses <1> to <8>, wherein a total width of the side regions is preferably 30% or more of the width of the topsheet, more preferably 40% or more, and 70% or less of a width of the topsheet, more preferably 60% or less.

<10>

The absorbent article as set forth in any one of clauses <1> to <9>, wherein the topsheet is configured such that, in the central region and each of the side regions, a second sheet-side surface is substantially flat, and large height undulations are formed on a first sheet-side surface.

<11>

The absorbent article as set forth in any one of clauses <1> to <10>, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the central region of the topsheet comprise a central first bonding portion and a central second bonding portion, the central first bonding portion and the central second bonding portion have rectangular shapes with sides extending in the longitudinal direction and sides extending in the lateral direction, and the shape of the central first bonding portion is different from the shape of the central second bonding portion.

<12>

The absorbent article as set forth in any one of clauses <1> to <11>, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the central region of the topsheet comprise central first bonding portions and central second bonding portions, the central first bonding portions are disposed so as to form first bonding portion rows where the central first bonding portions are arranged with a predetermined distance therebetween in the longitudinal direction, the central second bonding portions are disposed so as to form second bonding portion rows and third bonding portion rows where the central second bonding portions are arranged with a predetermined distance therebetween in the longitudinal direction, the second bonding portion row and the third bonding portion row are alternately disposed between the first bonding portion rows adjacent to one another, and a pitch, in the longitudinal direction, of the central second bonding portions included in the second bonding portion row is the same as a pitch, in the longitudinal direction, of the central second bonding portions included in the third bonding portion row, and the central second bonding portions included in the second bonding portion row are shifted by half pitch from the central second bonding portions included in the third bonding portion row.

<13>

The absorbent article as set forth in any one of clauses <1> to <12>, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the projections included in the central region comprise a central first projection and a central second projection, the central first projection have a substantially elliptical shape in plan view in which a length in the lateral direction is longer than a length in the longitudinal direction, the central second projection have a substantially circular shape in plan view in which a length in the lateral direction is substantially the same as a length in the longitudinal direction.

<14>

The absorbent article as set forth in any one of clauses <1> to <13>, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the side regions comprise a side first bonding portion and a side second bonding portion, the side first bonding portion and the side second bonding portion have rectangular shapes with sides extending in the longitudinal direction and sides extending in the lateral direction, and the shape of the side first bonding portion is different from the shape of the side second bonding portion.

<15>

The absorbent article as set forth in any one of clauses <1> to <14>, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the side regions comprise side first bonding portions and side second bonding portions, the side first bonding portions are disposed so as to form forth bonding portion rows where the side first bonding portions are arranged with a predetermined distance therebetween in the longitudinal direction, the side second bonding portions are disposed so as to form fifth bonding portion rows where the side second bonding portions are arranged with a predetermined distance therebetween in the longitudinal direction, the fourth bonding portion row and the fifth bonding portion row are alternately disposed in the lateral direction, a pitch of the side first bonding portions included in the forth bonding portion row is the same as a pitch of the side second bonding portions included in the fifth bonding portion row, and the side first bonding portions included in the forth bonding portion row are shifted by half pitch from the side second bonding portions included in the fifth bonding portion row.

<16>

The absorbent article as set forth in any one of clauses <1> to <15>, wherein the projections included in the central region comprise a central first projection and a central second projection the height of the central first projection is different from the height of the central second projection.

<17>

The absorbent article as set forth in any one of clauses <1> to <16>, wherein the height of the projections included in the central region is higher than the height of the projections included in the side regions, or the height of the projections included in the central region is the same as the height of the projections included in the side regions.

<18>

The absorbent article as set forth in any one of clauses <1> to <17>, wherein the arrangement pattern of the bonding portions is different between the central region and the side regions, and the shape of the bonding portions is also different between the central region and the side regions.

<19>

The absorbent article as set forth in any one of clauses <1> to <18>, wherein the area ratio of the bonding portions in the central region and the area ratio of the bonding portions in the side regions are preferably 10% or more, more preferably 15% or more and preferably 40% or less, more preferably 35% or less.

<20>

The absorbent article as set forth in any one of clauses <1> to <19>, wherein an area D is preferably 80% or less of an area C, more preferably 70% or less, and preferably 20% or more of the area C, more preferably 30% or more wherein the area C represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions, and the area D represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region.

<21>

The absorbent article as set forth in any one of clauses <1> to <20>, wherein a proportion of a total area of the bonding portions of an area C to a total area of the bonding portions in the central region is preferably 20% or more , more preferably 30% or more, and preferably 80% or less, more preferably 70% or less, wherein the area C represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions, and D represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region.

<22>

The absorbent article as set forth in any one of clauses <1> to <21>, wherein a proportion of a total area of the bonding portions of an area D to a total area of the bonding portions in the side regions is preferably 80% or more, more preferably 90% or more, and the upper limit of the proportion is preferably 100%, wherein C represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions, and the area D represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region.

<23>

The absorbent article as set forth in any one of clauses <1> to <22>, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, wherein a length F is preferably 80% or less of a length E, more preferably 70% or less, and preferably 20% or more of the length E, more preferably 30% or more, wherein E represents a length, in the longitudinal direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions.

<24>

The absorbent article as set forth in any one of clauses <1> to <23>, wherein a proportion of a total area of the bonding portions of length E to a total area of the bonding portions in the central region is preferably 20% or more, more preferably 30%, and the upper limit of the proportion is preferably 100%, wherein the length E represents a length, in the longitudinal direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions. <25>

The absorbent article as set forth in any one of clauses <1> to <24>, wherein a proportion of a total area of the bonding portions of a length F to a total area of the bonding portions in the side regions is preferably 60% or more, more preferably 80% or more, and the upper limit of the proportion is preferably 100%, wherein E represents a length, in the longitudinal direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and the length F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions. <26>

The absorbent article as set forth in any one of clauses <1> to <25>, wherein shearing stress of the central region takes a value of, preferably 25 N or more, more preferably 30 N or more, and preferably 34 N or less, more preferably 33 N or less.

<27>

The absorbent article as set forth in any one of clauses <1> to <26>, wherein shearing stress of each of the side regions takes a value of, preferably 33

N or more, more preferably 35 N or more, and preferably 45 N or less, more preferably

N or less under a condition that the shearing stress of each of the side regions is higher than the shearing stress of the central region.

<28>

The absorbent article as set forth in any one of clauses <1> to <27>, wherein a relationship Smax > Mmax is satisfied, wherein Smax represents an area of the projection that has the largest area among the projections in the central region, and Mmax represents an area of the projection that has the largest area among the projections in the side regions.

<29>

The absorbent article as set forth in any one of clauses <1> to <28>, wherein non-woven fabrics that are used as sheet materials for constituting the first sheet and the second sheet have a basis weight of, preferably 10 g/m² or more, more preferably 15 g/m² or more, and preferably 40 g/m² or less, more preferably 35 g/m² or less.

Examples [0056]

Hereinafter, the present invention will be described in further detail by way of examples. However, the scope of the present invention is not limited to the examples given below. Unless otherwise stated, % means mass%.

[0057]

Example 1

A disposable diaper was obtained by removing the topsheet of a Merries® disposable diaper (manufactured in 2015 by Kao Corporation), and then placing a topsheet as shown in Figs. 3 and 4 in place of the removed topsheet. The topsheet shown in Figs. 3 and 4 had bonding portions with the following dimensions: Sil: 1 mm * 4 mm; S12: 1 mm χ 1 mm, Mil: 1 mm x 4 mm, and M12: 1 mm x 3 mm (all of them were rectangular in shape).

As the first sheet constituting the topsheet, or in other words, the sheet to be placed on the wearer's skin-facing surface, an air-through non-woven fabric (basis weight: 18 g/m²) was used. As the second sheet, an air-through non-woven fabric (basis weight: 18 g/m²) was used. The air-through non-woven fabric constituting the first sheet had a two-layer structure composed of an upper layer and a lower layer, and the upper layer was made of core-in-sheath composite fibers (resin mass ratio: 5/5, 2.3 dtex, and core/sheath diameter ratio: 1.57) of polyethylene terephthalate and polyethylene. The lower layer was made of a cotton blend composed of core-in-sheath composite fibers (resin mass ratio: 5/5, 2.3 dtex, and core/sheath diameter ratio: 1.57) of polyethylene and polyethylene terephthalate, and core-in-sheath composite fibers (resin mass ratio: 5/5, 2.2 dtex, and core/sheath diameter ratio: 1.42) of polypropylene and low melting point polypropylene at a mass ratio of 5:5. The air-through non-woven fabric constituting the second sheet was made of core-in-sheath composite fibers (resin mass ratio: 5/5, and 2.3 dtex) of polyethylene terephthalate and polyethylene.

[0058]

Example 2

A disposable diaper was obtained in the same manner as in Example 1, except that a topsheet as shown in Fig. 6(a) was used as the topsheet in Example 1. The topsheet shown in Fig. 6(a) had bonding portions with the following dimensions: Sil: 1 mm x 2 mm, S12: 1 mm χ 1 mm, and Mil: 1 mm χ 1 mm (all of them were rectangular in shape).

[0059]

Example 3

A disposable diaper was obtained in the same manner as in Example 1, except that a topsheet as shown in Fig. 6(b) was used as the topsheet in Example 1. The topsheet shown in Fig. 6(b) had bonding portions with the following dimensions: Sil: 1 mm χ 3 mm, S12: 1 mm χ 1 mm, and Mil: 1 mm χ 1 mm (all of them were rectangular in shape).

[0060]

Comparative Example 1

A disposable diaper was obtained in the same manner as in Example 1, except that a topsheet in which only the bonding portions of the side regions of the topsheet used in Example 1 were formed over the entire region thereof was used as the topsheet in Example 1.

[0061]

Evaluation

The disposable diapers obtained in the examples and the comparative example were evaluated using the following methods in terms of the texture of the topsheet, and the degree of separation between sheets included in the topsheet. The results are shown in Table 1 given below.

[0062]

Softness of Topsheet

Ten mothers with infants who use diapers participated.

Each diaper was evaluated by the following criteria in terms of the softness of the surface material. The obtained results are shown in Table 1.

First, the topsheet of the Merries® disposable diaper (manufactured in 2015 by Kao Corporation) was touched, and the texture at that time was set as a reference (3 points). Then, evaluation was made based on five grades: 1 point (soft), 2 points (slightly soft), 3 points (as soft as Merries), 4 points (not so soft), 5 points (not soft), and softness was evaluated using the average value of the ten participants.

[0063]

Degree of Separation between Sheets in Topsheet

An acrylic plate was placed on a sample, a load was applied thereto such that the pressure reached 3.5 KPa, which is the pressure assumed to be applied when an infant is seated thereon, and then the acrylic plate was moved a predetermined number of times at a stroke length of 10 cm, and the degree of separation was visually checked and evaluated. The degree of separation of the topsheet of the Merries® disposable diaper (manufactured in 2015 by Kao Corporation) was defined as medium, the degree of separation lower than that was rated as “low”, and the degree of separation higher than that was rated as “high”.

[Table 1]

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[0065]

As is clear from the results shown in Table 1, the topsheets of the diapers of the examples have a better texture than that of the diaper of the comparative example. In addition, sheets are unlikely to separate from each other.

Industrial Applicability [0066]

The present invention provides an absorbent article that has a good texture and in which two sheets are unlikely to separate from each other and a gap is unlikely to form between the two sheets.

Claims (29)

1. An absorbent article comprising: a topsheet; a backsheet; and an absorbent member that is provided between the topsheet and the backsheet, wherein the topsheet comprises a stack including a first sheet and a second sheet, the stack includes a plurality of bonding portions formed by partially bonding the first sheet and the second sheet, and has a plurality of projections which protrude toward a body of a wearer, the projections being formed in such a manner that portions of the first sheet other than the bonding portions protrude in a direction away from the second sheet and, the topsheet includes a central region that is located at a center in a width direction of the topsheet and that extends in a lengthwise direction thereof, and a pair of side regions that extend in the lengthwise direction, the side region being adjacent to the central region, a shape and/or an arrangement pattern of the bonding portions are different between the central region and the side regions, an area ratio of the bonding portions is substantially the same between the central region and the side regions, and the number of the bonding portions per unit area is greater in the side regions than in the central region.

2. The absorbent article according to claim 1, wherein the topsheet has a relationship C > D, wherein C represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region, and D represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions.

3. The absorbent article according to claim 1 or 2, wherein the topsheet has a relationship E > F, wherein E represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions.

4. The absorbent article according to any one of claims 1 to 3, wherein the topsheet is configured such that each of the side regions of the topsheet has a higher shearing stress than the central region of the topsheet.

5. The absorbent article according to any one of claims 1 to 4, comprising:

a front portion that is to be placed on an abdominal side of a wearer when the absorbent article is worn;

a rear portion that is to be placed on a dorsal side of the wearer; and a crotch portion that is provided between the front portion and the rear portion, wherein the central region and the side regions are formed in the crotch portion.

6. The absorbent article according to any one of claims 1 to 5, comprising:

a front portion that is to be placed on an abdominal side of a wearer when the absorbent article is worn;

a rear portion that is to be placed on a dorsal side of the wearer; and a crotch portion that is provided between the front portion and the rear portion, wherein the central region and the side regions are formed so as to extend from the crotch portion to either one or both of the front portion and the rear portion.

7. The absorbent article according to any one of claims 1 to 6, wherein a width of the central region is 30% or more and 70% or less of a width of the topsheet.

8. The absorbent article according to any one of claims 1 to 7, wherein a width of each of the side regions is 15% or more and 35% or less of a width of the topsheet.

9. The absorbent article according to any one of claims 1 to 8, wherein a total width of the side regions is 30% or more and 70% or less of a width of the topsheet.

10. The absorbent article according to any one of claims 1 to 9, wherein the topsheet is configured such that, in the central region and each of the side regions, a second sheet-side surface is substantially flat, and large height undulations are formed on a first sheet-side surface.

11. The absorbent article according to any one of claims 1 to 10, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the central region of the topsheet comprise a central first bonding portion and a central second bonding portion, the central first bonding portion and the central second bonding portion have rectangular shapes with sides extending in the lengthwise direction and sides extending in the width direction, and the shape of the central first bonding portion is different from the shape of the central second bonding portion.

12. The absorbent article according to any one of claims 1 to 11, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the central region of the topsheet comprise central first bonding portions and central second bonding portions, the central first bonding portions are disposed so as to form first bonding portion rows where the central first bonding portions are arranged with a predetermined distance therebetween in the lengthwise direction, the central second bonding portions are disposed so as to form second bonding portion rows and third bonding portion rows where the central second bonding portions are arranged with a predetermined distance therebetween in the lengthwise direction, the second bonding portion row and the third bonding portion row are alternately disposed between the first bonding portion rows adjacent to one another, and a pitch, in the lengthwise direction, of the central second bonding portions included in the second bonding portion row is the same as a pitch, in the lengthwise direction, of the central second bonding portions included in the third bonding portion row, and the central second bonding portions included in the second bonding portion row are shifted by half pitch from the central second bonding portions included in the third bonding portion row.

13. The absorbent article according to any one of claims 1 to 12, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the projections included in the central region comprise a central first projection and a central second projection, the central first projection has a substantially elliptical shape in plan view in which a length in the width direction is longer than a length in the lengthwise direction, the central second projection has a substantially circular shape in plan view in which a length in the width direction is substantially the same as a length in the lengthwise direction.

14. The absorbent article according to any one of claims 1 to 13, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the side regions comprise a side first bonding portion and a side second bonding portion, the side first bonding portion and the side second bonding portion have rectangular shapes with sides extending in the lengthwise direction and sides extending in the width direction, and the shape of the side first bonding portion is different from the shape of the side second bonding portion.

15. The absorbent article according to any one of claims 1 to 14, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, the bonding portions included in the side regions comprise side first bonding portions and side second bonding portions, the side first bonding portions are disposed so as to form forth bonding portion rows where the side first bonding portions are arranged with a predetermined distance therebetween in the lengthwise direction, the side second bonding portions are disposed so as to form fifth bonding portion rows where the side second bonding portions are arranged with a predetermined distance therebetween in the lengthwise direction, the fourth bonding portion row and the fifth bonding portion row are alternately disposed in the width direction, a pitch of the side first bonding portions included in the forth bonding portion row is the same as a pitch of the side second bonding portions included in the fifth bonding portion row, and the side first bonding portions included in the forth bonding portion row are shifted by half pitch from the side second bonding portions included in the fifth bonding portion row.

16. The absorbent article according to any one of claims 1 to 15, wherein the projections included in the central region comprise a central first projection and a central second projection the height of the central first projection is different from the height of the central second projection.

17. The absorbent article according to any one of claims 1 to 16, wherein the height of the projections included in the central region is higher than the height of the projections included in the side regions, or the height of the projections included in the central region is the same as the height of the projections included in the side regions.

18. The absorbent article according to any one of claims 1 to 17, wherein the arrangement pattern of the bonding portions is different between the central region and the side regions, and the shape of the bonding portions is also different between the central region and the side regions.

19. The absorbent article according to any one of claims 1 to 18, wherein the area ratio of the bonding portions in the central region and the area ratio of the bonding portions in the side regions are 10% or more and 40% or less.

20. The absorbent article according to any one of claims 1 to 19, wherein an area D is 20% or more and 80% or less of an area C, wherein the area C represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions, and the area D represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region.

21. The absorbent article according to any one of claims 1 to 20, wherein a proportion of a total area of the bonding portions of an area C to a total area of the bonding portions in the central region is 20% or more and 80% or less, wherein the area C represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions, and D represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region.

22. The absorbent article according to any one of claims 1 to 21, wherein a proportion of a total area of the bonding portions of an area D to a total area of the bonding portions in the side regions is 80% or more and 100% or less, wherein C represents an area of the bonding portion that has the largest area among the bonding portions formed in the side regions, and the area D represents an area of the bonding portion that has the largest area among the bonding portions formed in the central region.

23. The absorbent article according to any one of claims 1 to 22, wherein the article comprises: a longitudinal direction that corresponds to a front-back direction of the wearer; and a lateral direction that is perpendicular to the longitudinal direction, wherein a length F is 20% or more and 80% or less of a length E, wherein the length E represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and the length F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions.

24. The absorbent article according to any one of claims 1 to 23, wherein a proportion of a total area of the bonding portions of a length E to a total area of the bonding portions in the central region is 20% or more and 100% or less, wherein the length E represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions.

25. The absorbent article according to any one of claims 1 to 24, wherein a proportion of a total area of the bonding portions of a length F to a total area of the bonding portions in the side regions is 60% or more and 100% or less, wherein E represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the central region, and the length F represents a length, in the lengthwise direction, of the bonding portion that has the longest length among the bonding portions formed in the side regions.

26. The absorbent article according to any one of claims 1 to 25, wherein shearing stress of the central region takes a value of 25 N or more and 34 N or less.

27. The absorbent article according to any one of claims 1 to 26, wherein shearing stress of each of the side regions takes a value of 33 N or more and 45 N or less under a condition that the shearing stress of each of the side regions is higher than the shearing stress of the central region.

28. The absorbent article according to any one of claims 1 to 27, wherein a relationship Smax > Mmax is satisfied, wherein Smax represents an area of the projection that has the largest area among the projections in the central region, and Mmax represents an area of the projection that has the largest area among the projections in the side regions.

29. The absorbent article according to any one of claims 1 to 28, wherein non-woven fabrics that are used as sheet materials for constituting the first sheet and the second sheet independently have a basis weight of 10 g/m2 or more and 40 g/m2 or less.